The present invention relates to a pattern carrier in form of a paper web with a colour pattern printed thereon and to be used in transfer pattern printing of a moist textile web. The invention relates also to the use of a saccharide syrup known per se as an ingredient in a dispersion for coating a paper web so as to obtain a pattern carrier with particular properties.
Transfer pattern printing is a well-known and extensively used technique, which involves a continuous transfer of a pre-printed pattern from a pattern carrier web to a moist textile web, where the two webs are continuously brought into contact with one another in a transfer region which is frequently in the form of one or more pairs of pressure rollers, cf. the Figure.
In principle various types of the technique have been known since the twenties but the technique did not become commercially interesting until the late fifties. Various types of transfer printing have been described inter alia in U.S. Pat. Nos. 1,651,470 and 1,783,606, FR-PS Nos. 1 034 816 and 1 036 510, DK patent applications Nos. 5666/68 and 1 566/69, SE-PS No. 137 674, GB-PS Nos. 1 430 832 and 1 480 328, U.S. Pat. Nos. 1,965,257 and 1,993,524, DE published specification Nos. 2 710 158 and 2 702 300 and U.S. Pat. No. 4,057,864. Common to the procedures described in these publications was that it was not possible to obtain acceptable results without involving a heating and/or dyes based on volatile organic solvents. Frequently, useful results required the use of so long contact times that it was in fact not a question of continuous printing processes.
Therefore it was a major breakhough for the transfer printing when the Applicant in the late eighties succeeded in developing a process for transfer pattern printing whereby it was possible simultaneously to avoid the heating and the use of organic solvents. The process is described in DK-PS No. 169 135 and is characterised by a suitable choice of pattern carrier and dye formulations, an accurate control of the moistening of the textile web and the use of a suitably high pressure, whereby particularly good reproducible results can be obtained at rather high processing speeds and, as mentioned, without the use of heating and exclusively by the use of water-based dye formulations. In addition to the production-related advantages and the particularly good product qualities, the process according to DK-PS No. 169 135 also presented obvious environmental and energy-related advantages as well as a substantially improved working environment.
This epoch-making process is, however, also subject to limitations. To be more precise this process presents particular requirements to the paper used as pattern carrier because said paper must be of a specific nature in order to be coated with a colour pattern at the desired printing speed. It is necessary to use a paper quality which is only slightly absorbing, and in order to avoid that the various, applied colours become blurred it is necessary to strongly cool the paper web between each application of colour in order to solidify the colour.
The printing of the paper is carried out by means of printing screens as shown in the Figure. Thus the process according to DK-PS No. 169 135 necessitates introduction of cooling rollers not shown between the individual printing screens. The coated paper web is carried around these cooling rollers while subjected to a cooling to below xe2x88x9220xc2x0 C. In this manner it is possible to prevent the colours applied from various printing screens from being blurred. However, this xe2x80x9cfreezingxe2x80x9d does, of course, complicate the entire process significantly and intensifies the costs involved, and accordingly it is desired to provide a pattern carrier where the colours do not become blurredxe2x80x94not even at high printing speeds, and which therefore does not require a cooling between the individual applications of colour.
Coating a paper surface with a suitably selected substance in order to alter the absorption properties of the paper is per se a well-known process. DE published specification No. 35 04 814 thus discloses a process for transfer pattern printing of a textile web, in which paper coated with for instance carboxymethylcellulose is used as a pattern carrier. DE accepted published specification No. 27 01 392 also discloses a process for transfer pattern printing of a textile material. Paper is used as a pattern carrier in this process, said paper being coated with carboxymethylcellulose and the dye being transferred from the pattern carrier to the textile by means of heat and/or pressure.
It is on the whole well-known to use carboxymethylcellulose as the substance with which a paper surface is coated. According to the above DK patent No 169 135 a pattern carrier of a lightly absorbing, preferably coated paper is thus used, the coating or application being made with carboxymethylcellulose, an alginate or an aqueous dispersion of polyethylene or polyacrylate, preferably carboxymethylcellulose which is an easily accessible substance with advantageous properties. However, the carboxymethylcellulose is per se not sufficient to provide standard-absorbing crude paper with the desired absorption properties.
The use of saccharides in the manufacture of transfer paper has hitherto only been described in JP patent application No 44-16135. However, this application relates to a transfer paper for transferring colour patterns to porcelain and ceramics. By adding one or several mono- or oligosaccharides to the water-soluble paste containing a cellulose derivate with which the paper is coated a paper is sought to be obtained which is more easily removed from the porcelain or ceramic object after the pattern has been transferred thereto. Furthermore, by using a transfer paper containing such saccharides, a pattern is obtained which retains its clear outlines after baking of the porcelain or ceramic object. The transfer paper according to the Japanese publication must be coated twice, the lower coating consisting of an aqueous solution of the cellulose derivative alone and the upper coating consisting of the same solution to which the chosen saccharide has been added. A water-resistant layer is subsequently applied on top of said layers, said water-resistant layer according to the examples being a 30% acetone solution of acetyl cellulose. This known transfer paper is thus considerably more complicated than the coated paper according to the present invention and is used for a completely different purpose.